"That's the first time anything like this has happened in 32 years," said Doug Baker, the founder and president of Mercy Flight, "as of this morning the mechanics still don't know what happened."

This is the timeline:

Sunday afternoon, the helicopter took off from the Mercy Flight Olean location responding to an emergency involving a child that was just over the Pennsylvania border. The chopper then reversed direction flying to Women and Children's in Buffalo to drop off the child. Around 6 p.m., when Mercy Flight was en route back to Olean, that's when the door fell off.

At the time, a pilot, paramedic and a nurse were on board, harnessed inside the aircraft.

"They tried to hold the door, the pilot tried to slow down the aircraft and in the midst of that the door came off," Baker said and that, "it happened very quickly and they landed very quickly and it was all over with within a matter of minutes."

The helicopter made an emergency landing in a field in Hamburg.

Baker says the protocol for Mercy Flight is to land as soon and as safe as possible.

After the incident, Baker says the FAA was immediately contacted. The FAA says there have be no accidents or incidents involving the chopper. Mercy Flight recovered the door near Herman Hill Road in North Boston, which is near where the chopper landed.

Meantime on Monday, mechanics at Mercy Flight are doing some extra review of their helicopters to make sure all of them are functioning well.

Other than the door falling off, there was some minor damage to the helicopter's blades. Baker says that the crew members, who are based in Olean, are all experienced first responders and that they're constantly trained to handle emergencies. Mercy Flight says the helicopter was inspected Sunday and that their helicopters are inspected daily.